chaparral vs fern

chaparral

noun
  • A region of shrubs, typically dry in the summer and rainy in the winter. The coast of the Mediterranean is such a region. 

  • The foliage of creosote bush, Larrea divaricata, when used as a medicinal herb. 

fern

noun
  • Any of a group of some twenty thousand species of vascular plants classified in the division Pteridophyta that lack seeds and reproduce by shedding spores to initiate an alternation of generations. 

How often have the words chaparral and fern occurred in a corpus of books? (source: Google Ngram Viewer )